Method and apparatus for neutralizing electrical disturbances



R. T. KNAPP Oct. 29, 1929.

METHOD AND APPARATUS FOR NEUTRALIZING ELECTRICAL DISTURBANCES Filed Jan. 25, 1927 4 Sheets-Sheet l INVENTOR. 3. I Y

ATTORN Y Oct. 29, 1 929. KNAPP 1,733,414

METHOD AND APPARATUS FOR NEUTRALIZING ELECTRICAL DISTURBANCES Filed Jan. 25, 1927 4 Sheets-Sheet 2 ESM IN V EN TOR.

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A TTORN Oct. 29, 1929. R. T. KNAPP 1,733,414

METHOD AND APPARATUS FOR NEUTRALIZING ELECTRICAL DISTURBANCES- Filed Jan. 25, 1927 4 Sheets-Sheet 5 3 INVENTOR.

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1929. R. T. KNAPP ,733, 14

METHOD AND APPARATUS FOR NEUTRALIZING ELECTRICAL DISTURBARCES Filed Jan. 25, 1927 4 Sheets-Sheet 4 *3: ATTORNEY Patented Oct. 29, 1929 UNITED STATES PATENT OFFICE RALPH T. KNAPP, OF MOUNT KISCO, NEW YORK, ASSIGNOR OF ONE-HALF TO HENRY N. JASPER, JR., OF MOUNT KISCO, NEW YORK METHOD AND APPARATUS FOR NEUTRALIZING ELECTRICAL DISTURBANCES Application filed January 25, 1927. Serial No. 163,431.

My invention relates broadly to radio re ceiving systems and more particularly to a circuit for the elimination of interference in radio receiving apparatus.

One of the objects of my invention is to provide a circuit arrangement for minimizing or eliminating from radio receivers the undesirable effects of natural atmospheric disturbances Whether aperiodic or periodic.

Another object of my invention is to provide a system of amplification for radio receiving apparatus with means for minimizing or eliminating from the receiving circuit the undesirable efiects of artificial atmospheric disturbances.

Still another object of my invention is to provide a circuit system for reception of signals where the receiver may be closely adjacent a transmitter without detrimental effect of the transmitter upon the receiving circuits.

A further object of my invention is to provide an arrangement of circuits for connection with a system of electron tubes in a radio receiving apparatus by which damped wave oscillations may be neutralized while continuous Wave signaling energy may be amplified for operation of a responsive device without interference from the damped Wave oscilla tions.

My invention will be more clearly understood from the specification hereinafter fol- 10 ing by reference to the accompanying drawings in which:

Figure 1 is a diagrammatic illustration showing the circuit arrangement embodying the principles of my invention; Fig. 2 is a modified arrangement of the circuits of my invention; Fig. 3 shows the application of the circuits to a radio frequency amplifier system in accordance with my invention; Fig. 4 shows a receiving circuit having independent radio frequency amplification systems for both the main receiving circuit and the side circuits; Fig. 5 shows my invention applied to a radio receiving system in which conductive coupling is employed between the main cir-' cuit and the side circuits; and Fig. 6 shows my invention applied to a radio receiving system in which capacitive coupling is employed between the main circuit and side circuits.

In its preferred form, my invention consists of three separate circuits each of which may include a detector. One of these circuits is coupled to the antenna and ground and ineludes its detector, and is referred to as the main circuit. The other two circuits which I have called side circuits, are coupled to the first or main circuit and adjusted so that their, natural frequencies are slightly different from those of the main circuit, the natural frequency of-one side circuit being slightly higher than that of the main circuit; and the natural frequency of the second side circuit being slightly lower than that of the main circuit.

If the main circuit is put into operation and is coupled to an output circuit as shown, the desired signals may be tuned in through the main circuit and will be evident at the output. Let these desirable signals be produced by continuous signaling oscillations or-by feebly damped signaling oscillations. Now the side circuits are coupled to the main circuit as described above and adjusted so that the first and second side circuits have natural periods of oscillation slightly above and below, respectively, that of the main circuit. The side circuits are adjusted so that they are not affected to any great extent by the desirable incoming signal but are affected by highly damped oscillations present in the main circuit. These side circuits are coupled so that their outputs are accumulative. These outputs are then brought into opposition to the output of the main. circuit. The audio frequency component of the highly damped oscillations may thus by suitable adjustment, be balanced out, or in other words, neutralized, leaving the audio frequency component. of the continuous si Referring to the drawings in more detail,

reference character 1 designates the antenna of a radio receiving installation, while ref erence character 2 designates the ground, both of which constitute the radio frequency energy collecting circuit. The antenna system may be tuned by variable condenser 3 and may be connected to primary inductances and 5 as illustrated in Fig. 1 or merely to the single inductance 4: as illustrated in the other diagrams. These inductances constitute part of the main circuit. The side circuits of the receiver may be coupled inductively or conductively .or capacitively to the main circuit which is connected directly to the antenna system. The main circuit may,

however, be coupled to the antenna system through any suitable apparatus. The main circuit includes the electron tube 6 having grid, filament and plate electrodes 6, 6 and 6", respectively. 'The input circuit of tube 6 includes grid leak and grid condenser 7 in series with the grid 6 the main circuit from tube-6 is passed through the primary winding of audio frequency transformer 8 having secondary winding 9. There are two side circuits, one of which S comprises electronv tube 10 withcondenser 11 coupled by means of inductance 12 to inductance 4 and the other of which S comprises electron tube 14 having condenser 15 coupled through inductance 16 with primary in ductance 5. The output circuit of the elec-,

tron tube 10 includes the primary winding of audio frequency transformer 17 having secondary winding 18. The outout cir-' cuit of electron tube 14- includes t e pri mary winding of an audio frequency transformer 19 having secondary winding 20. The primary winding of' each of the audio frequency transformers 8, 17, and 19'is shunted by'means of by-pass condensers 8 17' and 1-9.

. respectively. Thesecondary windings 18 and cumulative. audio frequency transformer 8 is connected 20'of audio frequency transformers 17 and 19 respectively are connected in. series as shown in such manner that their outputs are The secondary winding 9 of in series with the other two secondary windings as shown, so that its output opposes that of the combined transformer secondaries 18 V L that of the main circuit, depending upon the and 20 of the side circuits. Inotherjwords,

The output of the outputs from windings 18 and 20 are integrated while the output from winding 9 is such, that. like oscillations in secondary winding 9 and also secondary windings 18 and 20combined oppose and neutralize each other.

The resultant current components are supplied to the input circuit of electron tube 21. The output of electron tube 21 may be connected to a cascade audio frequency amplifier at terminals 22 and then to a suitable responsive device In Fig. 2, I have shown a single primary inductance 4 in the main circuit-connected to the input circuit of electron tube detector 6 and to this inductance 4 there is coupled the inductance 12 of the side circuit 8,. To this same inductance 4 maybe coupled the secondary winding16 of the side circuit S The main circuit shown is tuned to the desired incoming signal. This signal may be either one of continuous oscillations or one of feebly damped oscillations. At the same time, this circuit may have in it oscillations produced by aperiodic and periodic atmospheric disturbances. "The aperiodic strays will produce oscillations in the main circuit by shock while the periodic disturbances will produce oscillations in the main circuit of an intensity-dependent upon the frequency and decrement of .the incoming disturbances. That is, theband of highly, damped periodic oscillations within which the main circuit will respond is wider than the band of continuous or freely damped oscillations within which it will respond.

The band of highly damped oscillations within which each sidecircuit will respond is wider than the band of feebly damped or continuous oscillations within which each will respond. Each sidecircuit is adjusted so that its natural frequency is either higher or lower than that of the main circuit, the difference being great enough so that feebly damped or continuous signaling oscillations, depending upon their characteristics, present in theinain circuit will affect the side circuits little, ifat all.

However, since each side circuit will respond to highly damped oscillations, as explained above, -it;will respond to part or all of the highly damped oscillations in the main circuit, depending upon the char acteristics of the oscillations. Each side circuit is designed to be affected only by those oscillations. which arepresent in .the main circuit. r --It isseen that there maybe highly damped oscillations in the main circuit of a frequency outsideoftheband within which side circuit S, is responsive. coupled to the main circuit and is made re- Side circuit S, is

sponsive tothese highly damped oscillations. The natural frequency of oscillation of side circuit S is adpistedhigher or lowervthan' llt) adjustment of side circuit S If side circuit S is adjusted to a higher natural fre-' quenc than the main circuit, then side circuit adjusted than the main circuit or vice versa.

Side circuit is adjusted so that it will respond little, if atall, to the band of feebly and which would be outside of the frequency band witnin which side circuit S is responsive will now be well within the frequency band within which side circuit S is responsive. The same is true of highly damped oscillations present in the main circuit which may be outside of the frequency band within which side circuit S is responsive, as they will be well within the frequency band with in which side circuit S is responsive.

It is clear that when the apparatus is adjusted properly, little if any energy of the feebly damped or continuous oscillations present in the main circuit will be transferred to either of the side circuits. Consequently,

signals of this character will not be balanced out or neutralized. However, energy of i highly damped oscillations present in the main circuit will be transferred to one or both of the side circuits. VJ hen these side circuits are properly adjusted, the eifects of the energ 7 so transferred will be cumulative and can be balanced against the like effects of energy in the main circuit and so balance 1 out or neutralize any effects of highly in which 18 1ncluded.

damped oscillation, static disturbance.

Considering the case in which neutralization is accomplished at audio frequency, it

will be seen that one or both of the side circuits S, and S Wlll respond to everyhighly damped periodic and aperiodic oscillation present in the main circuit, but both side circuits S, and S will respond little, if at all, to continuous or feebly dan' ped oscillations present in the main circuit. The outp'utsof the two side circuits S, and S are so. in- 1 tegrated that the resultant audio frequency component of every highly damped periodic and a eriodic oscillation'in them will be' equivalent to the audio frequency component of the original oscillations present in the;

main circuit. These audio frequency'compoand thus bann ed out or neutralized. I

In Fig. 3, I have shown the circuit are to a lower natural frequency rangement of my invention employed in conjunction with a radio frequency amplifier constituted by electron tubes 23 and 24: disposed before the main receiving circuit com prising electron tube 6 and the side circuits including electron tubes and 14. The radio frequency. amplifier may include any number of stages of amplification with the output circuit thereof providedwith an inductance to which the side circuits S and S are coupled through inductances 12 and 16. The output of the balance or neutralizing circuit which includes the secondaries of trans formers 17, 8 and 19, connects through audio frequency amplification stages 21 and 25 to the responsive device 26.

In Fig. 4 I have illustrated independent radio frequency amplification systems for each of the side circuits which are in addition to the radio frequency amplification system in the main circuit. The side circuit which includes detector 10 is coupled through a radio frequency amplifier constituted by tubes 27 and 28 with the input circuit 11 which couples through inductance 12 with the inductance l. The side circuit which includes the detector tube 14 connects with the input circuit 15 through electron tubes 29 and 30. By this arrangement of radio frequency amplification, the amplitudes in the main circuit as well as in the side circuits, may be independently controlled.

I11 Fig. 5, I have illustrated the inductance l provided with a plurality of adjustable taps. These adjustable taps lead to the different detector circuits constituted by electron tubes 6, 10 and 14. Taps 31 connect with the input of detector tube 10. Taps 82 connect with the input of detector 6, while taps 33 connect with the input circuit of detector tube 14. The position of these taps is regulated until desired operating position is obtained. The circuit containing electron tube 6 constitutes the main circuit while the circuits containing electron tubes 10 and 14 constitute the side circuits.

1 In Fig. 6-, I have illustrated a form of my invention in which capacitive coupling between the side circuits and the main circuit is employed. The circuits containing the electron tubes 10 and 14 constitute the side circuits while the circuit containing the electron tube 6 constitutes the main circuit.

Each of the detectors or a selected one of the detectors may be of the autodyne type for het'erodyning with the continuous wave incoming signaling oscillations.

The principle of my invention may be understood by considering the two side circuit-s coupled to the main circuit which contains the incoming oscillations. The side circuits will respond to highly damped oscillations covering a wider band of frequencies than they will to feebly damped or continuous oscillations. These side circuits are tuned so that their natural frequencies ofoscillation are one above and the other below that of the main circuit. lVhile the feebly damped or continuous oscillations will not be trans- V ferred from the main circuit to the side .cir cuits at any considerable amplltude by reason of the circuit adjustments, the highly damped oscillations will be transferred from the main circuit to the side circuits and are balanced-out or neutralized leaving the feebly damped or continuous.oscillations to proceed to the output circuit. I

The balancing or neutralizing may be effected in a variety of different ways without changing the nature of my invention. The

' balancing may occur at radio or at audio fre- V cillations.

quency. That is, the tubes 6 l0 and 14 shown in the circuits of Fig. 2, may be operated as radio frequency amplifiers instead of detectors, and the audio frequencytransformers shown will be radio, frequency transformers in this case, the detector action occurring at tube 21.

I have described my invention in certain preferred embodiments but I desire that it be understood that modifications. in detail may be made fbythose skilled in the art without departing from the vspirit of my invention, and that no limitations are intended other than are imposed vby the scope of the appended claims.

What I claim as new and desire to secure by Letters Patentof the United States isas follows:

l. A radio receiving system comprising a radio frequency .energy collecting circuit, .a main circuit connected thereto, sidecircuits each including means for tuningtoa frequency different from those of the other side-circuit and said main circuit, a detectorin each of said side circuits, an output circuit .connected to ,each detector, audio frequency transformers having primary and secondary windings, with the primary windings. thereof included in said output :ci-rcuits, a plurality of said secondary windings being cumulatively connected, While another of said secondary windings is connected in opposition thereto for neutralizing :the effects of objectionable damped wave oscillationsv in said receiving circuits, and means forampli fying continuous wave or desirable damped wave signaling energy independent of interference from. objectionable damped wave os- 2; A radio receiving system for wave signaling energy comprising a radio frequency energy collecting circuit including a main circuit, side circuits connected with said main circuit, each-of said side circuits including-a detector and each including means responsive to a frequency different from those of theside circuit and the main circuit, a responsive device, audio frequency transformers having :primary and secondary windings,

with the primary windings thereof connected with each of said detectors, and the secondary windings thereof connected both cumulatively and differentially for impressing the effects of continuous wave or desirable damped wave signaling energy on said responsive device while neutralizing the effects of obj ectionable oscillations.

3. In a signal receiving system, a radio frequency energy collecting circuit, a main circuit connected to said radio frequency energ 1 collecting circuit, side circuits connected' with said main circuit, each of said side circuits including means responsive to a band of frequencies different from those of the other side circuit andmain circuit, adetector connected to each of said side circuits, a responsive device, audio frequency transformers eachshaving primary and secondary windings, with the primary windings thereof individually connected with each of said detectors, said transformers having a pair of secondary windings thereof cumulatively connected and connected in opposition with another of said secondary windings for neutralizing the effects of objectionable damped oscillations while integrating the effects of continuous wave or desirable damped wave signaling energy upon said responsive device.

4. A signal receiving system comprising a radiofrequency energy collecting circuit, a main cilcuit connected' in said radio frequency energy collecting circuit, side circuits coupled with said main circuit and each including means responsive to a band of frequencies di iferent from those ofthe other side circuit and main circuit, adetector connected to eaohof said side circuits, a responsive device, an audio frequency transformer having primary and secondary windings, with the primary windings thereof individually connected with saiddetector, circuitconnections between. said responsive device and said secondary windings, including a pair of secondary windings cumulatively connected and another of-said secondary windingsconnected in opposition thereto for neutralizing the effects of objectionable damped oscillations while impressing continuous wave or desirable damped wave signaling energy upon said responsive device.

.5.- A radio receiving system comprising a. radio. frequency energy collecting circuit, a

7 primary circuit included'therein, a secondary circuit coupled .to said primary circuit, a detector included in said secondary circuit, a pair of side circuits each independently cou' pled :to said primary circuit and each including means: adjustableto respond to a band of frequencies different from those of the other side-circuit and main circuit, a detector included ineach of said side circuits, a responsive device, ,audio frequency transformers each having primary and secondary windings, with the primary windings thereof connected with said detectors, and the secondary windings thereof connected in series and with said responsive device, a pair of said secondary windings being cumulatively connected and arranged in opposition with respect to anothe secondary winding for neutralizing the effects of objectionable damped oscillations upon said responsive device, while impressing continuous wave or desirable damped wave signaling energy upon said responsive device.

6. A radio receiving system comprising a high frequency energy collecting circuit, a primary system included therein, a secondary system coupled with said primary system, said secondary system being divided into a main circuit and a pair of side circuits, a detector connected in each of said circuits, audio frequency transformers having primary and secondary windings, with the primary windings thereof individually connected to said detector circuits, and the secondary windings, one of said side circuits being reof said secondary windings being disposed in opposition to the pair of secondary wind ings of the audio frequency transformers associated with said side circuits, a responsive device connected with said secondary windings, one of said side circuits being responsive to a frequency band above the frequency band of said main circuit and the other of said side circuits being responsive to a frequency band below the frequency range of said main circuit, while impressing continuous wave or desirable damped wave signaling energy upon said responsive device.

7. A signal receiving circuit comprising a primary circuit system, a secondary system coupled with said primary system, said secondary system being divided into a main circuit and a pair of side circuits, a detector connected in each of said circuits, audio frequency transformers having primary and secondary windings with the primary windings thereof individually connected to said detector circuits and the secondary windings thereof connected in series, another of said secondary windings being disposed in op position to the pair of secondary windings of the audio frequency transformer associated with said side circuits, a responsive device connected with said secondary windings, one of said side circuits being adjusted to a frequency range above the frequency band of said main circuit and the other of said side circuits being adjusted to a frequency range below the frequency range of said main circuit.

8. In a system for receiving high frequency signal-bearing energy the method of receiving said energy to the effective exclusion of accompanying interfering disturbances which consists of resonantly receiving the signalbearing energy accompanied by some of the disturbing energy, receiving in a plurality of components said distrubing energy non-resonantly with respect to said signal-bearing energy, detecting all received energies, and opposing the detected component of the resonantly received energy with an in-phase combination of the detected components of the non-resonantly received energies.

9. In a system for receiving high frequency signal-bearing energy the method of receiving said energy to the effective exclusion of accompanying interfering disturbances which consists of resonantly receiving the signal bearing energy accompanied by some of the disturbing energy, receiving said disturbing energy both above and below resonance with respect to said signal-bearing energy, detecting all of said energies, and opposing the detected component of the resonantly received energy with an in-phase combination of the detected components of the other energies.

10. In a system for receiving high frequency signal-bearing energy the method of receiving said ener y to the effective exclusion of accompanying interfering disturbances which consists of resonantly receiving the signal-bearing energy accompanied by some of the disturbing energy, receiving said disturbing energy both above and below resonance with respect to said signal-bearing energy, and opposing the resonantly received energywith an in-phase combination of the other energies before responsive translation thereof.

11. In a system for receiving high frequency signal-bearing energy to the effective exclusion of accompanying interfering disturbances including a receiving system tuned to said signal-bearing energy, a detector in said system, a translating device associated therewith, a pair of receiving systems differently attuned from said receiving system and each qther, detecting means in each of said systems, and means for opposing the detected energy received by said first system by an inphase combination of the detected energies of said pair of systems before translation in said translating device.

12. In a system for receiving high frequency signal-bearing energy to the effective exclusion of accompanying interfering disturbances including a receiving system tuned to said signal-bearing energy, a detector in said system, a translating device associated therewith, a pair of receiving systems, one tuned above and the other tuned below said first system, detecting means associated with each of said systems, and means for opposing the detected energy received by said first system by an in-phase combination of the detected energies of said pair of systems before translation in said translating device.

18. In a system for receiving high frequency Elgiiitlrbal'll'lg energy he the efiective exclusion of- ;iceompanying interfering disturbances including a receiving system tuned to said signal-bearing energy, a pair of receiving systems, one tuned above and the other tuned below said first system, detecting means and translating means associatedwith all of said systems, and means for opposing the energy received by the first said system by an in-phase combination of the energies received by said pair of systems before impressing; said energies upon said translating device.

- RALPH T. KNAPP. 

